Complete screening and quasiatomic MVV auger line shapes due to double core ionization

MVV spectra of ph, Pd, and Ag were measured with and without ionization of their L-3 levels. Extra (MMMVV) structure corresponds to the M45M45 --> M45 VV transition following the L3M45M45 transition. We interpret the MMMVV str ucture for Pd as quasiatomic in nature from its similarity to the correspon ding Ag spectral shape and from its agreement with atomic calculations. The Pd quasiatomic MMMVV spectrum arises from a two final-state hole bound sta te in the Pd d band filled by screening of the core holes. These findings r epresent the first unambiguous observation of the influence of complete scr eening on spectral features.